692 TEXT-BOOK OF PHYSIOLOGY. 



few weeks the mass loses its red color and becomes decidedly yellow, when it 

 is known as the corpus luteum. With the continuance of reparative changes 

 this body gradually disappears until at the end of two months nothing 

 remains but a small cicatrix on the surface of the ovary. Such are the 

 changes in the follicle if the ovum has not been impregnated. 



The corpus luteum, after impregnation has taken place, undergoes a 

 much slower development, becomes larger, and continues during the entire 

 period of gestation. The difference between the corpus luteum of the un- 

 impregnated and pregnant condition is expressed in the following table by 

 Dalton: 



CORPUS LUTEUM OF MENSTRUATION. CORPUS LUTEUM OF PREGNANCY. 



At the end of three Three-quarters of an inch in diameter; central clot reddish; convoluted 

 weeks. wall pale. 



One month j Smaller; convoluted wall bright | Larger; convoluted wall bright yellow; 



yellow; dot still reddish. clot still reddish. 



Two months i Reduced to the condition of an 



insignificant cicatrix. 



Four months . . . i Absent or unnoticeable . . . 



Six months Absent. 



Nine months . . . Absent . 



Seven-eighths of an inch in diameter; con- 

 voluted wall bright yellow; clot perfectly 

 decolorized. 



Seven-eighths of an inch in diameter; clot 

 pale and fibrinous; convoluted wall dull 

 yellow. 



Still as large as at the end of second 

 month; clot fibrinous; convoluted wall 

 paler. 



Half an inch in diameter; central clot con- 

 verted into a radiating cicatrix; external 

 wall tolerably thick and convoluted, but 

 without any bright yellow color. 



THE REPRODUCTIVE ORGANS OF THE MALE. 



The reproductive organs of the male comprise the testicles, vasa deferen- 

 tia, vesiculae seminales, and penis. 



The Testicles. The testicles are oblong glands, about 40 mm. in 

 length, 30 mm. in breadth and 20 mm. in thickness, and contained within 

 the cavity of the scrotum. A section of the testicle (Fig. 348) reveals the 

 presence externally of a dense fibrous membrane, the tunica albuginea, and 

 internally a connective-tissue framework consisting mainly of septa, which 

 enter the organ on its posterior aspect at the mediastinum testis, passing in- 

 ward in a diverging manner. The spaces between the septa are occupied 

 by the true gland substance, the seminiferous tubules. 



The seminiferous tubules are very numerous, the estimate as to their 

 number varying from 800 to 1000. When unraveled they measure from 30 

 to 40 cm. in length and 0.3 mm. in diameter. At their peripheral extremities 

 the tubules are very much convoluted, but as they pass toward the mediasti- 

 num testis, the convolutions disappear, and after uniting with one another 

 terminate in from twenty to thirty straight tubes, of small diameter, 

 the vasa recta, which pass through the mediastinum and form the rete testis. 

 At the upper part of the mediastinum the tubules unite to form from nine 

 to thirty small ducts, the vasa efferentia, which soon become very much con- 

 voluted. After a short course they unite to form a single tortuous tube, 

 about 7 meters in length and 0.4 mm. in diameter, which descends behind 



